Why can't I add other extensions to my project?

I am using the restaurant extension and when I click on "add more +" it takes me to the extensions page and all the extensions have a "trash/delete" option but nothing to click and add to the project.I am trying to add a "text editor" since this stupid restaurant theme won't allow me to input lunch and dinner hours. As soon as I add more hours all the operation hours get out of whack.This is my first project and I have bought the entire extension options and activate them.Can anyone shed light on this?Thank you

This is really frustrating, last time I sent a help email to Mobirise it took them 5 days to respond.I guess this a page out of Skype- their goal was to make it impossible to contact them. nice business model

I see that part of the confusion is with the terminology. What you're referring to are "themes", like RestaurantM4 is a Theme, Blockpack is a theme, etc. Some of the items in that screenshot you gave us ARE "extensions" though, like the PayPal thing, or social media. In both cases, they add blocks to the "+" menu in your lower-right corner.

On to your actual question: Can I use blocks from Blockpack in my RestaurantM4-themed site? The answer (for this particular combination) is no. You CAN however use blocks from any theme with M4 in the name in sites based upon any other theme with M4 in the name,

Example: Create a new site with (for example) CommerceM4. Select a block you like. Customize it even. If you hover your mouse in the upper right cornet OF THE BLOCK you get the block menu... one of the items there is a download symbol, hovering over it reveals the function: Save to User Blocks. Click this. You'll see an animation of your chosen block being put into the block menu on the right.

Ok, now open up your real site, say.. based on RestaurantM4. Open the block menu (click the "+"), and at the very top of the block menu are 4 buttons.. Show All, Theme, Extension, and User. Click User to see only the "User" blocks (blocks that have been saved in the above method). The block you saved earlier is there, and now you can use it in your RestaurantM4 site.

Remember, you cannot save and reuse blocks from v3 of Mobi like this - you can save M3 blocks (M3 themes do NOT have M3 in the name, while ALL M4 blocks do). If you save an M3 block it can only be used in the site it was saved from. Bummer.

So, stick with M4 themes only and you can mix and match blocks all you want.